Heating tube and baffle for deep fat fryers

ABSTRACT

The invention is directed to an improved heating tube for deep fat fryers and particularly to a baffle which is inserted in the heating tube, said baffle consisting of an elongated strip of metal having projections struck out from alternate sides of the strip, said projections being placed at varying angles from the strip depending upon the distance between each projection and the point at which a flame enters the heating tube.

U ited states Patent [191 Parker 1 Nov. 6, 1973 HEATING TUBE AND RAFFLEFOR DEEP FAT FRYERS [75] Inventor: James W. Parker, Chicago, 111.

[73] Assignee: Chicken Unlimited, Inc., Chicago, 111.

[22] Filed: Mar. 2, 1972 [21] Appl. No.: 231,226

52 U.S.Cl 126/91,165/109, 165/185,

I g v 138/38 51 Int. Cl .4 rzs: 7 00 58 Field ofSearch 126/91 A, 99 A;165/109 T, 179, 185; 138/38 [56] 7 References Cited *UNITED STATESPATENTS 2,655,944': 10/1953 Proehl 126/91 A 9/1954 OBrien 165/109 T9/1958 Lynn 165/109 Primary ExaminerCharles Sukalo Att0meyJohnston,Root, OKeefe, Keil, Thompson & Shurtleff 5 7 ABSTRACT The invention isdirected to an improved heating tube for deep fat fryers andparticularly to a baffle which is inserted in the heating tube, saidbaffle consisting of an elongated strip of metal having projectionsstruck out from alternate sides of the strip, said projections beingplaced at varying angles from the strip depending upon 1 the distancebetween each projection and the point at which a flame enters theheating tube.

5 Claims, 4 Drawing Figures BACKGROUND OF THE INVENTION This inventionis directed to an improved heating tube for deep fat fryers and to aremovable baffle for said heating tube, said baffle including oppositelydisposed and angularly arranged projections.

Restaurants, hospitals, and other establishments which regularly preparefried foods such as fried chicken and the like, use deep fat fryerswhich hold substantial volumes of melted fat or oil. The fat or oil ismaintained at a temperature on the order of 375-430F. The volume of fator oil held in the fryer is considerably larger than the volume ofmaterial to be fried. Such a large volume is needed to prevent excessivechilling of the heated fat or oil when frozen or cold articles such aschicken parts are placed in the fryer.

Because of the large volume of oil or fat used in such fryers it isimportant to have a highly efficient means to heat the fat or oil and toreplace the heat that is used up during the frying operation. It iscustomary to heat the fat or oil by means of a gas flame'or flames whichcontact horizontal heat exchanger or combustion tubes within the fryertank; Heat energy is passed from the flame to the walls of' the tubesand then to the oil or fat in the cooking vessel.

In tubular heat exchangers there is a tendency for the heat from theflame to pass through the tube and to be lost with the exhaust gases upthe flues or stacks of the heating system. To prevent this heat lossdevices such as heating grids, baffles and the like have been added tothe tubes. These are designed to break up and radially deflect the'flameto effect a more efficient transfer of heat from the heat exchanger tothe heated medium. There is also a tendency for the heated gases withinthe heating tube to form a concentric series of films or laminae fromthe core to the inner circumference of the tube. These concentric filmsor laminae tend to move successively slower from the core outwardly tothe circumference wherethe film or laminae in frictional contact withthe inner surface of the tube wall mvoes the slowest. Under suchconditions, heat transfer between the heat exchanger and theimedium tobe heated is not optimal. To break up the films or laminae which form inthe tubes, it has been common practice to incorporate in the tubes somekind of baffle.

The construction of such baffles and other devices has assumed a varietyof patterns in an attempt to obtain more efficient heat transfer.Despite the use of such baffles, the prior art devices have not beenentirely successful. Uniform heating of the fat or oil has beendifficult to maintain, particularly where the baffle or deflector iswelded to the heat tube thereby forming points of double insulation.Additionally, certain of the heating tubes sufferfrom burn-out whichnecessitates the replacement of the entire tube. The formation ofexcessive amounts of carbon monoxide gas is also a problem with certainprior art devices.

OBJECTS OF THE INVENTION One of the primary objects of the presentinvention is to provide a more efficient heat transfer means for deepfat fryers. A further object of the invention is to provide a baffle ofa type which is easily manufactured from strip material and which may beconveniently inserted and removed from heat exchanger tubes. A stillfurther object of the invention is to provide a baffle havingprojections alternately formed from the sides of the strip, whichprojections may be punched, stamped, or otherwise bent outwardly fromthe strip itself. A further object of the invention is to provide a heatexchanger which improves the heat efficiency of the heating tube and yetdoes not produce undue amounts of carbon monoxide gas. Other objectswill become apparent to those skilled in the art from the followingdetailed description of the invention.

SUMMARY OF THE INVENTION In general, the present invention consists ofan improved heating tube and heat exchanger for use in a deep fat fryer.The heat exchanger includes a baffle comprising an elongated strip ofheat resistant metal having a series of oppositely disposed, angularlyarranged tabs or deflectors. Each of the tabs is arranged at apredetermined angle with respect to the strip. The angle formed betweenthe tabs and the strip varies with the distance between the tab and theend of the heat exchange tube.'The angles are selected to providemaximum heat transfer to the heating medium while causing a minimumformation of carbon monoxide gas.

DESCRIPTION or THE DRAWINGS FIG. I is a perspective view of a heatingtube containing the subject baffle;

FIG. 2 is a side view of the subject baffle;

FIG. 3 is a top plan view of the baffle; and

FIG. 4 is a sectional view taken along lines 4-4 of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS ably positioned within the tube10. A handle 14 is attached to or forms a part of the baffle 13. Thehandle is at the gage end of the tube. The handle can be calibrated soas to regulate the distance between the opening of the tube and thefirst tab or projection 15 of the baffle. The baffle includes a seriesof such projections (15-21) which are spaced at various distances fromthe opening of the tube. As is evident from FIG. 3, the angle between aprojection and, the baffle strip increases as the distance from the tubeopening to the projection increases. The number of such projectionsdepends largely on the length of the heating tube and the baffle. One ofthe advantages of the subject device lies in the fact that the baffle isremovable. In case of a burn-out a new baffle can be inserted in thetube without difficulty and without great expense.

FIG. 2 is a side view of the baffle. Projections 15-21 are struck fromthe baffle strip. The distance between the projections is approximatelyequal and in one commercial embodiment is about 5/16 inches. In the sameembodiment the projections are from inches to We inches wide and 2inches from top to bottom, while the length of the baffle is 9 inchesand its height is 4 inches.

FIG. 3 is a top plan view of the baffle of FIG. 2. The angle betweenbaffle 13 and projection 15 is 10. The angle between projection 16 andbaffle 13 is 13. The angle between projection 17 and the baffle is Theangle between projection 18 and the baffle is 24. The angle betweenprojection 19 and the baffle is 28. The angle between projection 20 andthe baffle is 32, and the angle between projection 21 and the baffle is38. The angles of the individual projections can be varied up to plus orminus 3 and, preferably, the variation from the stated amount should notbe greater than plus or minus 1.

FIG. 4 is a sectional view taken along lines 4-4 of FIG. 2. The strip ofbaffle 13 is shown, as well as projections 18 and 19.

As was pointed out previously, gas burners are conventionally used toheat the fat or oil in the tank. It has been found that the use of twosmall gas burners per heating tube is satisfactory for most purposes.The baffle strip 13 splits the flames of the burners and the projectionsdeflect the flames outwardly toward the walls of the tubes. 1f 75 poundsof shortening oil is placed in the fryer, 10 burners, each with acapacity of 14,070 btus can be employed. This provides a total of140,700 btu input into the cooker.

Both the baffle and the heating tube can be made of heat resistant metalsuch as Nichrome steel. Because there are no weld points between thebaffle and the tube, no metal burnout is experienced with the subjectdevice. A lack of weld points also promotes uniform heating of the fator oil. Although most of the heating tubes are hexagonal or oval, a widevariety of tube shapes can be used with the subject baffle. Many of thetubes used in commercial establishments are about 16 inches in length.

1 claim:

1. A heat exchanger for use in a deep fat fryer which comprises incombination: a metal combustion chamber and a flame-deflecting baffleremovably positioned with said chamber, said baffle including anelongated metal strip and a series of oppositely disposed and angularlyarranged metal deflectors extending from said strip, said deflectorsforming an angle with said strip which becomes progressively larger asthe distance between the deflector and the inlet opening of saidcombustion chamber increases.

2. A heat exchanger as in claim 1 wherein said baffle includes anelongated handle for positioning said baffle within said combustionchamber.

3. A heat exchanger as in claim 1 wherein said baffle includes at leastseven deflectors arranged on alternate sides of the elongated metalstrip of the baffle, and wherein the angle between the deflector closestto the inlet opening of the combustion chamber and said metal strip isfrom 7 to 13, the angle between the second deflector and the metal stripis from 10 to 16, the angle between the third deflector and the metalstrip is from 17 to 23, the angle between the fourth deflector and themetal strip is from 21 to 27, the angle between the fifth deflector andthe metal strip is from 25 to 31, the angle between the sixth deflectorand the metal strip is from 29 to 35, and the angle between the seventhdeflector and the metal strip is from 35 to 41.

4. A heat exchanger as in claim 3 wherein the angle between thedeflector closest to the inlet opening of the combustion chamber andsaid metal strip is from 9 to 11, the angle between the second deflectorand the metal strip is from 12 to 14, the angle between the thirddeflector and the metal strip is from 19 to 21, the angle between thefourth deflector and the metal strip is from 23 to 25, the angle betweenthe fifth deflector and the metal strip is from 27 to 29, the anglebetween the sixth deflector and the metal strip is from 31 to 33, andthe angle between the seventh deflector be accurately regulated.

1. A heat exchanger for use in a deep fat fryer which comprises incombination: a metal combustion chamber and a flame-deflecting baffleremovably positioned with said chamber, said baffle including anelongated metal strip and a series of oppositely disposed and angularlyarranged metal deflectors extending from said strip, said deflectorsforming an angle with said strip which becomes progressively larger asthe distance between the deflector and the inlet opening of saidcombustion chamber increases.
 2. A heat exchanger as in claim 1 whereinsaid baffle includes an elongated handle for positioning said bafflewithin said combustion chamber.
 3. A heat exchanger as in claim 1wherein said baffle includes at least seven deflectors arranged onalternate sides of the elongated metal strip of the baffle, and whereinthe angle between the deflector closest to the inlet opening of thecombustion chamber and said metal strip is from 7* to 13*, the anglebetween the second deflector and the metal strip is from 10* to 16*, theangle between the third deflector and the metal strip is from 17* to23*, the angle between the fourth deflector and the metal strip is from21* to 27*, the angle between the fifth deflector and the metal strip isfrom 25* to 31*, the angle between the sixth deflector and the metalstrip is from 29* to 35*, and the angle between the seventh deflectorand the metal strip is from 35* to 41*.
 4. A heat exchanger as in claim3 wherein the angle between the deflector closest to the inlet openingof the combustion chamber and said metal strip is from 9* to 11*, theangle between the second deflector and the metal strip is from 12* to14*, the angle between the third deflector and the metal strip is from19* to 21*, the angle between the fourth deflector and the metal stripis from 23* to 25*, the angle between the fifth deflector and the metalstrip is from 27* to 29*, the angle between the sixth deflector and themetal strip is from 31* to 33*, and the angle between the seventhdeflector and the metal strip is from 37* to 39*.
 5. A heat exchanger asin claim 2 wherein said handle is calibrated whereby the distancebetween the opening of said chamber and the first deflector of saidstrip can be accurately regulatEd.